Channel process oil enrichment



Sept- 27, 1955 C. BILLINGS ET AL CHANNEL PROCESS @1L ENRICHMENT Filed Jan. l1, 1951 nited States Patent CHANNEL PROCESS OIL ENRICHIVIENT Curtis Billings and Roy vW. Darwin, Pampa, Tex., as-

signors to Godfrey L.- Cabot, Inc., Boston, Mass., a corporation of Massachusetts Application January 11, 1951, Serial No. 205,522

4 Claims. (Cl. 23-209.8)

This invention relates to the production of carbon v.black by the channel process, that is, by the irnpingement of a hydrocarbon flame against a relatively cool surface. VMore particularly it comprises an improved process for producing channel carbon blacks from gas enriched with normally'liquid hydrocarbons.

Because liquid hydrocarbons are much richer in carbon than is `natural gas and because the yield of carbon from certain, particularly the aromatic, liquid hydrocarbons is considerably higher than that from natural gas the use of such liquid hydrocarbons as a raw material for carbon black production is highly advantageous. On the other hand there are serious operating diiculties encountered when using liquid hydrocarbons in a channel plant.

In order to achieve maximum benefits and eiciency in the production of channel carbon black it is necessary `that the hydrocarbon flame be relatively small. Consequently the gaseous raw material is introduced into the reaction zone through myriad small widely distributed orifices or tips shaped in accordance with the desired flame shape. For example, the tips may be slotted to provide a wide thin ame, or may have a cylindrical bore to provide the so-called rat tail llame. Whatever the shape of the orifice it is small, rarely exceeding about 0.033 square inch in cross-sectional area.

It has been found that hydrocarbons in the liquid state cannot be passed through so small a tip without quickly forming coke at the high temperatures existing in the vicinity of the tips. As the usual 140 ft. hot building contains some 3,000 of these tips it can readily be appreciated how serious the coking and eventual plugging of any number of these tips would be.

During more than half a century various attempts have been made to enrich natural gas for channel black production with liquid hydrocarbons. In every case, so far as we are aware, the method of enrichment has followed the same pattern, namely, vaporization of the liquid hydrocarbons prior to mixing with the gas. Examples of such method are illustrated by UnitedStates Letters Patent Nos. 491,923, Cabot and 1,838,316, Lewis. It is evident that such methods are-cumbersome and require the use of considerable heating equipment to vaporize the liquid materials, and hence are expensive both to build and to maintain.

We have discovered that, contrary to expectation, liquid hydrocarbons having certain prescribed qualities under certain critical conditions can be introduced directly into the gas stream entering the hot house.

It is the principal object of our invention to provide an improved process of producing standard type channel carbon blacks at high yields by adding liquid hydrocarbons directly to the gas supplied to the channel hot house.

It is also an object of our invention to provide an improved process for enriching the natural gas raw material with liquid hydrocarbons.

It is still another object of our invention to provide a method of introducing a liquid hydrocarbon kinto the car- Patented Sept. 27, 1955 bon black forming reaction zone of a channel plant in any gaseous material such as hydrogen, air, etc. v

We accomplish these and other objects of our invention by introducing a hydrocarbon oil having a distillation end point below about 950 F in a very'ne stream into the vmain supply pipe of each channel hot house at a rate of flow such that all or substantially all of the oil will be evaporated into the gas before the gas passes'into the vertical risers within the hot house. Under the conditions prevailing in most present day channel plants the rate of oil flow should not ordinarily exceed about 1.6 gallons per 1000 cu. ft. of gas and will preferably not exceed about 0.4 gallon per 1000 cu. ft. of gas. However, these How rates will vary depending upon the composition and temperature of the gas and of the oil, and .the ranges of permissible ilow rates may be substantially `greater than those stated.

Our invention will better be understood and appreciated from the following description of a preferred manner of carrying it out illustrated in the accompanying drawing showing a typical channel hot house and equipment in perspective, portions of the house and of its interior equipment being cut away.

The channel carbon .black plant includes a hot `house 10, a plurality of burner pipes 1'2 extending horizontally almost the entire length of the hot house, which may be -200 ft. in length, and being equipped with a multiplicity of burner tips 14 throughV which the gas flames are fed. A channel member 16 is suspended over each longitudinal gas pipe 12. Air to support combustion of the gas liowing from tips 14 enters the hot vhouse beneath the side walls. Excess air and products of combustion pass out of the hot house through stack 18 and openings 20.

Carbon black is formed in these many gas llames to which insuicient air for complete combustion is supplied and is deposited by inipingement upon the under surface of the channels 16 from which it is removed, as the channels slowly reciprocate, by scrapers (not shown) held against the depositing surface. The black scraped o falls into hoppers and thence into a screw-conveyor for ultimate recovery. The collection equipment referred to is not shown in the drawing as being standard equipment in the-channel carbon black industry.

-Gas is supplied to the hot house through supply pipe 22 provided with the usual valve 23 and orce ange 24, connected into a gas main which supplies all of the other yhot houses in a producing unit which may include 60 hot houses, more or less. From supply pipe 22 the gas is distributed, about midway of the hot house, through a cross-pipe 25, here shown as being of substantially larger diameter than that of the supply pipe but which may be of the same diameter, to a pair of parallel ground pipes 26 which extend the full length of the hot house. Risers 28 carry the gas to manifolds 30 through which the gas is distributed to longitudinal burner pipes 12. Each hot house may contain some three thousand burner tips 14 of lava or steatite, each tip supplying from approximately 45 to 80 cubic feet of gas per 24 hour day. Gas ows for the entire hot building may range from 150,000 to as high as 260,000 cu. ft. of gas per `24 hr. day. Y

When burning natural gas alone in the channel process and with the aid of dame shields and air guiding devices within the hot house 10 the maximum yield of carbon black obtainable is about 21/2 lbs. per thousand cu. `ft. of gas burned. There are various reasons for this low yield condition: The reaction time is short, a large excess of `air is of necessity supplied which causes much of the gas to `be burned to supply heat for dissociation of the .re-

mainder and a substantial quantity of black escapes detion rate is also limited, principally because at higher gas and air flows proportionately greater quantities of carbon black are carried off in the gases. Additionally there is a limit to the amount of gas that can be supplied, beyond which the channels and tips will rapidly be destroyed by over heating.

It has long been known that higher yields and higher production rates are possible when liquid hydrocarbons in the vapor state have been added to the natural gas raw material. However, as we have said, it has not heretofore been considered possible to add normally liquid hydrocarbons directly to the gas stream except as a vapor.

We have discovered that liquid hydrocarbons can be introduced directly into the gas stream by following the practice of our invention.

In the practice of our invention we can use any liquid hydrocarbon having a distillation end point of below about 950 F., which material is hereinafter referred to as the oil. Oil from a main supply pipe 32 is taken off by a branch pipe 34 and passed through filter 36. As this filter must be very fine the oil is preferably maintained under a pressure of between about 25 and 50 p. s. i. g. A pressure gauge 37 is provided for each hot house oil supply line. From the filter the oil is carried through a pipe 38 and through a very fine orifice, drilled in a blank secured within coupling 40, which largely controls the rate of oil flow. For ows from l to gals. of oil per hour the orifice is of capillary size, being in the order of about 0.02 inch in diameter. Slightly larger orifices are used for higher rates of flow. The oil passing through this orifice then drips or flows in a very fine stream through pipe 42 into gas supply pipe 22. The oil may be delivered to supply pipe 22 at a point near the hot house inlet end as shown in the drawing or at any convenient downstream point. A draw-off cock 44 and shut off valve 45 are provided to permit cleaning out of the line when and if necessary.

The rate at which the oil can be added to the gas supply depends upon the rate of gas ow, the vapor pressure of the oil and the temperature of the gas in the main supply line. Thus, for example, at gas ows to the hot height above the ground, and rapidly increases in temperature as it passes through ground pipes 26, risers 28 and manifolds 30. At tips 14 the gas probably attains a temperature of about l,000 F.

5 In the course of travel through the hot house pipe systern the oil, originally present in the form of a gas-oil mixture, evaporates rapidly into the gas stream so that none of the oil is in a liquid state by the time it reaches the burner tips.

We prefer to use a cross-pipe of somewhat larger diameter than the supply pipe in order to facilitate the evaporation of the oil into the gas by providing in effect an evaporation chamber. We have found that with a 3" supply pipe 22 a cross-pipe 25 having a diameter of 8 is particularly effective.

The amount of increased yield obtainable from the oil depends to some extent, at least, upon the characteristics In the following example are set forth the results of typical runs in an arbitrary unit of one commercial channel hot house utilizing the process of our invention, the examples including analytical qualities of easy processing channel (EPC) carbon blacks produced therefrom and from natural gas alone and of rubber compounded with such blacks.

Example 1I Standard Run EPC-Gas D68 D69 D71 D72 D73 D74 only 7.08 7.08 7.08 7. 91 6.26 7.08 7. 08 1.9 1. 95 2.0 2.0 2.0 3.0 Total yield, lbs/hr 14. 2 1S. 95 19.7 20. 8 17. 5 19. 2 21. 7 Yield attributable to oil alone, lbs/gal 2. 5 2. 8 2. 5 2. 5 2. 5 2. 5 Scale (N igrometer) 1 85.1 86. 5 87.0 84. 4 85.5 84.7 84. 8

COMPOUNDED IN NATURAL RUBBER Flexometer, Mins., ASTM D623-41T 44. 0 55. 0 60. 0 45. 0 44. 0 45. 0 44. 0 Rebound, Percent Restored Energy 70.1 71. 5 72.1 69.0 70.0 70.5 68. 7 Torsional hysteresis 0.225 0. 227 0. 193 O. 263 0. 256 0. 233 0. 25 300 Modulus, lbs/sq. in 1, 690 1, 740 1, 720 1, 740 1, 690 1, 790 1, 760 Tensile, lbs/sq. in 4, 390 4, 420 4, 390 4, 600 4, 470 4, 500 4, 740 Electrical Resistance, megohrns/cu. cm 12 22 58 2 2 4 5 1 Lower nigrometer figure indicates blacker color.

house of about 150,000 cu. ft. per 24 hr. day an oil having a distillation end point of about 640 F. can be introduced at the rate of from l to l0 gals. per hr. into gas ranging in temperature from 215 F. for a one gal. per hour flow rate to 309 F. for a flow of l0 gals. per hour, the gas being preheated to those temperatures.

The temperature of the gas in the plant main is, of course, that of the surrounding ground. As the gas flows into the hot house through supply pipe 22 it is rapidly heated so that by the time the gas reaches the cross-pipe 25 it is at a temperature of about 250 F. or higher, depending upon the length of pipe 22 and its Of considerable importance is the use of carbon blacks in ink. The nature of the black largely determines the flow characteristics of the ink. Such characteristics are usually determined in the ink industry by preparing a mixture comprising l5 parts carbon black and 85 parts of a standard lithographie ink vehicle, aging the mixture one day and then measuring the rate of flow of a 3 gram sample of this ink down a glass plate inclined at an angle of from the horizontal. As shown in the following example the inks prepared from carbon blacks produced in accordance with our invention possess How characterstics superior to those containing duced from natural gas alone.

Example III carbon blacks pro- It may be noted that incremental yields from the above oils average about 21/2 lbs. per gallon. From oils of higher aromaticity We conclude that yields of as high as 4 lbs. of black per gallon of oil may be obtainable by the practice of our invention.

It will be evident that by the practice of our invention it is possible to achieve not only uniform enrichment of gaseous raw material with oil in the liquid state but also to attain as high a loading of the gas as is possible with oil in the vapor state. Furthermore, the process of our invention is remarkable for its simplicity, economy and ease of operation. Preheating equipment is not necessarily required as the oil may be introduced at atmospheric temperature. Furthermore, any oil can be used having an end point below about 950 F., which even includes residual oils from which the heavy non-distillable fractions have first been removed either prior to introduction into the gas supply line, or at some point in the gas supply line. Not only are substantially increased yields obtained but also, and, in some eases more irnportantly, the production rate of carbon black is greatly increased since the enriching oil carried to the reaction zone is of relatively small volume.

Aside from a slight loss in color, the qualities of the black produced by the process of our invention are identical to those of blacks produced from natural gas alone. Furthermore, the loss of color can readily be compensated for by changing tip distance or by following other expedients well known to those skilled in the art.

This invention is in some respects an improvement over that described in copending application Serial No. 154,016, now Letters Patent No. 2,665,194, January 5, 1954, of Merrill E. Jordan.

Having thus disclosed our invention and described in detail an illustrative example of satisfactory apparatus for carrying out our improved process, what we claim as new and desire to secure by Letters Patent is:

1. A process for the production of channel carbon black which comprises flowing a liquid hydrocarbon having a distillation end point below about 950 F. in the liquid state directly into a stream of combustible gas at a uniform rate not in excess of that at which substantially all of said liquid hydrocarbon will evaporate into the gas in the course of its subsequent flow through a heated fuel distribution zone, conducting the liquid hydrocarbon-gas mixture through said heated distribution zone in a circuitous path to a carbon black producing and deposition zone, burning said mixture under conditions of incomplete combustion against relatively cool surfaces, thereby depositing carbon black thereon and heating said distribution zone, and recovering the carbon black thus produced.

2. The process of claim l in which the liquid hydrocarbon is injected into the gas stream at a point at which the gas is at a temperature below that of the boiling temperature of the liquid hydrocarbon.

3. The process of claim 1 in which the combustible gas is natural gas.

4. In a process for the production of channel carbon black in which natural gas ows through a system of horizontal supply pipes, vertical risers and horizontal distribution pipes equipped with a plurality of burner tips, and is burned at the tips under conditions of incomplete combustion against the underside of channels whereby carbon black is deposited on said channels; the improvement which comprises introducing a liquid stream of hydrocarbon oil having a distillation end point below about 950 F. into the horizontal supply pipes at a rate not in excess of that at which substantially all of the oil will evaporate into the gas while in said supply pipes, thereby enriching the gas and increasing the yield of carbon black for any given volume of gas ow.

References Cited in the tile of this patent UNITED STATES PATENTS 343,446 Dysart June 8, 1886 491,923 Cabot Feb. 14, 1893 911,464 Vaughn Feb. 2, 1909 1,838,316 Lewis Dec. 29, 1931 1,860,598 Rumbarger May 31, 1932 1,932,537 Straight Oct. 3l, 1933 1,993,315 Blackwood Mar. 5, 1935 2,081,130 Atwell May 25, 1937 2,109,136 Markle et al. Feb. 22, 1938 2,225,354 Schmalenbach Dec. 17, 1940 2,375,796 Krejci May 15, 1945 2,499,438 Wiegand et al. Mar. 7, 1950 

1. A PROCESS FOR THE PRODUCTION OF CHANNEL CARBON BLACK WHICH COMPRISES FLOWING A LIQUID HYDROCARBON HAVING A DISTILLATION END POINT BELOW ABOUT 950* F. IN THE LIQUID STATE DIRECTLY INTO A STREAM OF COMBUSTIBLE GAS AND A UNIFORM RATE NOT IN EXCESS OF THAT AT WHICH SUBSTANTTIALLY ALL OF SAID LIQUID HYDROCARBON WILL EVAPORATE INTO THE GAS IN THE COURSE OF ITS SUBSEQUENT FLOW THROUGH A HEATED FUEL DISTRIBUTION ZONE, CONDUCTING THE LIQUID HYDROCARBON-GAS MIXTURE THROUGH SAID HEATED DISTRIBUTION ZONE IN A CIRCUITOUS PATH TO A CARBON BLACK PRODUCING AND DEPOSITION ZONE, BURNING SAID MIXTURE UNDER CONDITIONS OF INCOMPLETE COMBUSTION AGAINST RELATIVELY COOL SURFACES, THEREBY DEPOSITING CARBON BLACK THEREON AND HEATING SAID DISTRIBUTION ZONE, AND RECOVERING THE CARBON BLACK THUS PRODUCED. 